Impact-Increment Based Reliability Assessment Method For Power System And Integrated Energy System

The reliable and stable operation of power system is the basis and prerequisite of social stability and economic development.In addition,as the basis of future energy supply,integrated energy systems(IESs)should ensure safe and reliableoperation.This thesis focuses on the reliability assessment method of power system and integrated energy system based on the impact-increment.The main works are summarized as followed:1.An impact-increment Monte Carlo reliability assessment method is proposed,which effectively improves the computational efficiency of Monte Carlo method for large-scale transmission system.First,taking into account the characteristics of the sampling frequency of the Monte Carlo method,a calculation formula for the reliability index based on the impact-increment is proposed.Then,a reduction technique is developed to further eliminate higher order contingency states.Finally,the annual load curve is introduced so that the proposed method can practically calculate the reliability index.The proposed method can effectively improve the computational efficiency of the Monte Carlo method for large-scale transmission system.2.An incremental reliability assessment method for transmission expansion planning is proposed.First,contingencies are categorized into three scenarios according to the states of the added components of the planning schemes.Then contribution of each scenario to the incremental reliability indices is analyzed in detail.It turns out that contingencies of only one scenario can affect the incremental reliability indices and therefore other contingencies can be eliminated.Based on this phenomenon,an incremental reliability assessment method is developed for transmission expansion planning.Besides,the number of evaluated contingencies can be further reduced by the proposed relevant contingency search algorithm.This method can calculate the incremental reliability index more accurately and efficiently for the transmission expansion planning schemes.3.A contingency partition method to coordinate system planning and operation is proposed.First,the loss of load would be calculated based on the security correction strategy.Then,the loss of load risk can be calculated based on the impact-increment method,and the quantification of contingencies risk index can be obtained.Finally,the proposed method uses loss of load risk index to clarify the responsibilities between operation and planning.The proposed method is verified in the practical system and the study results demonstrate the feasibility of the proposed method.4.An impact-increment reliability assessment approach to IESs is introduced.The optimal load curtailment algorithm and reliability assessment algorithm are both improved in the proposed approach.For the optimal load curtailment problem,the proposed approach develops a hierarchical decoupling optimization framework for both the energy hub optimal dispatch and the optimal power flow problems.This feasible solution can make the optimal load curtailment calculation more efficient and accurate.For the reliability assessment algorithm,an impact-increment based state enumeration method is accommodated for IESs to accelerate the reliability assessment process.Also,a reduction technique of higher order contingencies is presented for the reliability evaluation of IESs to further enhance the computational efficiency.The integrated energy test system case and practical system case verify the efficient and robust performance of the proposed approach.Besides,the impacts of energy conversion process and energy hubs on IESs reliability are analyzed in detail.